Three-dimensional electronic map data creation method

ABSTRACT

When creating three-dimensional electronic map data, three-dimensional modeling of a building is performed as follows without measuring height of the building. Firstly, a building is photographed and the photographing position and photographing parameters (camera direction, angle of view) are recorded. Secondly, in a virtual space prepared on a computer, a photograph is arranged so as to reproduce the state upon the photographing according to these data. In combination with this, a plan view of the building is arranged according to the two-dimensional map data. Thirdly, the plan view is moved in the height direction until it is overlapped with the photograph, thereby modeling the building. Thus, it is possible to realize three-dimensional modeling without measuring the height.

TECHNICAL FIELD

The present invention relates to a three-dimensional modeling method ofgenerating three-dimensional electronic data of a building structure, aswell as to a technique of generating three-dimensional electronic mapdata by taking advantage of the three-dimensional modeling method.

BACKGROUND ART

Use of map data converted in a computer processible form (hereafterreferred to as ‘electronic map data’) has recently been spread tovarious fields. The electronic map data are used for display of maps onpersonal computers, navigation systems mounted on vehicles, display ofmaps via the Internet, and production of mechanicals for maps in print.Three-dimensional display is adopted in the navigation system to helpthe driver's intuitive understanding of the drive course.Three-dimensional display of building structures advantageously assiststhe user's easy specification of the current position and the drivecourse.

Three-dimensional data of the building structures are required for thethree-dimensional display. Extensive labor is, however, required toobtain three-dimensional data, especially height-relating data, withregard to a large number of building structures as objects of display inthe maps. Diverse techniques have been proposed to relive such enormouslabor. Examples of the proposed techniques include a technique disclosedin Japanese Patent No. 3015353 and ‘Simulation in Automatic Measuring ofThree-Dimensional Urban Space Data in Range Images’, Ghao Huijing et al.(Institute of Industrial Science, University of Tokyo), Vol. 36, No. 4,1997, ‘Photogrammetry and Remote Sensing’, Japan Society ofPhotogrammetry and Remote Sensing. The former technique aims to relievethe load of data acquisition by ingeniously setting a measurement pointof the height of a building structure and the direction of measurement.The latter technique acquires three-dimensional data by matching theresults of ranging with a laser range finder with CCD images.

In order to attain three-dimensional modeling of a building structurewith lack of three-dimensional data, the conventional method assumes afixed height regardless of the actual height of the building structure,or estimates the height of the building structure by the number ofstories. These methods, however, do not sufficiently reflect the actualstate and only give pseudo three-dimensional modeling.

The conventional three-dimensional modeling method requires measurementof each building structure to effectuate modeling that sufficientlyreflects the actual state. Three-dimensional modeling of a huge numberof building structures is required to generate practicalthree-dimensional electronic map data. The above proposed techniquesthus do not sufficiently relive the labor but still demand an extremelylarge amount of labor for generation of the three-dimensional electronicmap data.

In the span of several years, some new building structures areconstructed and some old building structures are demolished. In order toensure the practical use of the three-dimensional electronic map data,three-dimensional modeling should be performed at intervals followingsuch a change of the building structures. The conventional techniques,however, require a long time for three-dimensional modeling and thus donot meet this time-based demand.

DISCLOSURE OF THE INVENTION

The object of the present invention is thus to solve the problems of theprior art techniques and to provide a method of labor-saving yetpractical three-dimensional modeling that reflects the actual state of abuilding structure. The object of the invention is also to provide atechnique of readily generating three-dimensional electronic map data bytaking advantage of the three-dimensional modeling method.

In order to attain at least part of the above and the other relatedobjects, the present invention is directed to a three-dimensionalmodeling technique without requiring measurement of a height. Thistechnique carries out matching of a photograph of a building structurewith its planar shape in a virtually provided space, for example, withthe aid of a computer. The description first regards the principle ofthree-dimensional modeling in the present invention, prior to discussionof the construction of the invention.

FIG. 1 shows the principle of three-dimensional modeling in the presentinvention. The illustration gives a virtual space provided on a displayDISP of a computer. The virtual space is defined in a three-dimensionalcoordinate system of, for example, latitude, longitude, and altitude. Atthe initial stage, only a ground surface GRD in the virtual spaceappears on the display DISP.

The procedure locates a photograph PIC of a building structure as anobject of three-dimensional modeling (hereafter simply referred to asthe object) and a planar shape PV of the object in the virtual space.The photograph PIC is located, based on various pieces of informationincluding a shooting position, an orientation of a camera, and an angleof view at the time of photographing. The photograph PIC thus locatedrepresents an image PB, which is to be displayed if the object ispresent in the virtual space. The planar shape PV of the object isreadily obtained by existing two-dimensional map data.

The procedure then shifts the planar shape PV in parallel in thedirection of height as shown by the lower drawing. This creates avirtual three-dimensional model of the planar shape PV in the virtualspace. As mentioned above, the photograph PIC gives the image PB to bedisplayed if the object is present in the virtual space. Overlap of thethree-dimensional model obtained by the parallel shift of the planarshape in the direction of height with the image PB means that thethree-dimensional model reflects the actual height of the object. Theprocedure shifts the planar shape in the direction of height toreproduce the actual scene taken by photographing, thus attaining thethree-dimensional modeling of the object.

The principle of the invention is discussed with reference to thedisplay of the computer shown in FIG. 1. The discussion further regardsthe principle of the invention according to the shooting conditions.FIG. 2 shows the relation between a photographed image and a buildingstructure. The upper drawing and the center drawing respectively show aplan view V1 and a side view V2 at the time of photographing. The lowerdrawing shows a photograph PIC obtained.

As shown in the plan view V1, two building structures BLDa and BLDb arepresent in the range of an angle of view θ of a camera DSC. These twobuilding structures BLDa and BLDb have similar heights in the photographPIC, but actually have different heights Ha and Hb as shown in the sideview V2. The range of the building structures is expressed by a thickline in the photograph PIC included in the side view V2. The top of thethick line is naturally located on a line segment of connecting thecamera DSC with the tops of the building structures.

The procedure of the invention reproduces the positional relation shownin FIG. 2 in the virtual space, thus effectuating three-dimensionalmodeling. The heights of the building structures BLDa and BLDb areunknown in the initial stage of modeling in the virtual space. Locationof the camera DSC and the photograph PIC corresponding to the positionalrelation at the time of shooting causes the tops of the buildingstructures BLDa and BLDb to be present on an extension of the buildingstructures (expressed by the thick line) in the photograph PIC. Overlapof the top of the model obtained by parallel shift of the planar shapein the direction of height in the virtual space with the top of thephotograph well reproduces the positional relation of FIG. 2 in thevirtual space. This arrangement specifies the heights of the respectivebuilding structures BLDa and BLDb in the virtual space without measuringthe actual heights thereof.

The above description shows the principle of three-dimensional modelingof the invention. The discussion is based on the concrete example shownin FIGS. 1 and 2, for the better understanding of the principle. Thepresent invention is thus not restricted to such description in anysense. The construction of the invention based on the principle isdiscussed below.

The three-dimensional modeling method of the invention has the stepsdiscussed below. The step (a) inputs a photograph of the buildingstructure expressed by electronic data. The input of the photograph maybe attained by inputting electronic data of a digital still camera or byinputting electronic data of a conventional photograph with a scanner orthe like. The photograph may not show the whole building structure butis required to include at least an upper portion of the buildingstructure.

The step (b) inputs a positional relation between a shooting position ofthe photograph and the building structure and a shooting parameterrequired to fit the photograph to an actual scene of viewing thebuilding structure from the shooting position. The positional relationand the shooting parameter are utilized as data for reproducing theshooting conditions in the virtual space. The shooting position is notrequired to be defined by absolute coordinates of, for example, latitudeand longitude, but is sufficient to be defined by the relative positionto the building structure. The absolute coordinates of, for example,latitude and longitude may be used to specify the shooting position andthe position of the building structure, according to the requirements.

The shooting parameter may be any of various parameters that specify theorientation of the camera and the angle of view at the time of shooting.FIG. 3 shows the angle of view of the camera. A focal length f denotes adistance between a lens L and a shooting unit CCD. The focal lengthspecifies the angle of view, that is, the width of a range OBJ possiblytaken by the shooting unit CCD. The angle of view θ and the focal lengthf may thus be used for the shooting parameter.

FIG. 4 shows the shooting direction of the camera. Axes X, Y, and Z inthe illustration correspond to the axes in a virtual space. The latitudeand the longitude may microscopically be regarded as orthogonalcoordinates, so that the axes X and Y may be mapped to the latitude andthe longitude. In the virtual space of the defined three axes, theshooting direction of the camera is specified by a yaw angle α, a pitchangle β, and a roll angle γ. Namely these angles may be used asparameters for specifying the shooting direction. The shooting directionmay be specified by a diversity of other parameters, but the set ofthree angles shown in FIG. 4 advantageously facilitates acquisition ofthe parameters at the time of photographing.

After input of the shooting parameter, the step (c) defines a planarshape of the building structure and the shooting position in a virtualspace set for generation of the three-dimensional electronic data, basedon the input positional relation, and arranges the photograph at aposition specified by the input shooting parameter. It is not necessarythat the planar shape of the building structure is perfectly specifiedas a closed figure as in the example of FIGS. 1 and 2. The onlyrequirement is to specify a planar shape corresponding to the faceincluded in the photograph. The planar shape may thus be a line segmentor polygonal line.

The step (d) maps the defined planar shape in a direction of height tobe matched with the photograph, so as to specify a shape of the buildingstructure in the direction of height. The mapping may be performedmanually by an operator or may be carried out automatically.

The three-dimensional modeling method of the invention efficientlycreates a three-dimensional model without measuring the height of eachbuilding structure. Compared with the conventional pseudo estimation ofthe height of a building structure by the number of stories, this methodattains three-dimensional modeling with a remarkably higher accuracy.

When one photograph includes multiple building structures, thethree-dimensional modeling method of the invention advantageouslyimplements simultaneous three-dimensional modeling of the multiplebuilding structures, based on this photograph. The photograph used maynot be taken on the ground. Application of an aerial photographfacilitates three-dimensional modeling in a wide range.

As mentioned above, it is not necessary to completely specify the planarshape used in the three-dimensional modeling method of the invention.One preferable procedure, however, specifies the planar shape by atwo-dimensional plane map including the building structure. The planarshape of the high accuracy results in three-dimensional modeling of thehigh accuracy.

In one preferable embodiment of the three-dimensional modeling method ofthe invention, the step (c) defines a three-dimensional base modelgiving a rough contour of the building structure, as well as the planarshape. The building structures include houses of relatively complicatedshapes, as well as office buildings of relatively simple shapes. Thethree-dimensional base models are used to classify building structuresaccording to their shapes, for example, into office buildings and housesand to define the rough contours of the respective classified buildingstructures. Application of the base model in addition to the planarshape defines the rough shape of the building structure including thedirection of height. This ensures labor-saving yet accuratethree-dimensional modeling.

The step (d) in the method of the invention may manually be carried outby an operator or may automatically be performed by, for example, acomputer. In the latter case, the step (d) includes the sub-steps of:analyzing the photograph to specify an edge of the building structure;quantitatively analyzing an overlap status of a side of the planar shapewith the specified edge in the course of mapping; and selecting amapping of a local maximum overlap to specify a height of the buildingstructure. The ‘local maximum’ overlap may not be the greatest overlap.In the course of auto analysis, the overlap state significantly variesby the effects of noise. The concrete procedure thus filters out suchnoise and specifies the map of a substantially maximum overlap.

In one preferable application of the invention, the three-dimensionalmodeling method reflects the altitude of ground surface in the vicinityof the building structure. Such reflection is allowed by the process ofinputting altitude data representing an altitude of ground surface inthe vicinity of the building structure, making the input altitude datareflect on the ground surface in the vicinity of the building structure,and specifying the shape of the building structure by taking intoaccount the altitude data. The method of specifying the shape based onthe altitude data may specify the shape of the building structure in thedirection of height, above the ground surface on which the altitude datais reflected. This arrangement ensures accurate specification of theheight of the building structure.

The three-dimensional modeling method of the invention may furtherinclude a step (e) of attaching at least part of the photograph as atexture to surface of a resulting model of the building structure havingthe specified shape in the direction of height. The photograph used forattachment as the texture may be separately provided from the photographused for specification of the height. Application of the photograph onthe surface of the model relatively easily enhances the touch of realityin modeling.

In the case of applying the photograph to the texture, one preferableprocedure separately deals with a repetition area, in which a relativelysimilar unit structure appears repeatedly, from a residual single area.For example, the step (e) may define the repetition area and the singlearea and repeatedly attaches a texture of the unit structure to therepetition area, whether an actual structure is included or not includedin the photograph. This facilitates attachment of the texture in therepetition area and enhances the practical use of the texture. In theactual state, trees and other obstacles located on the front side of abuilding structure often interferes with taking a photograph of the faceof the building structure. The repeated attachment technique applies aphotograph representing part of the repetition area to the wholerepetition area, and thus relatively easily relieves the effects of theobstacles.

The present invention is directed to a three-dimensional electronic mapdata generation method of generating three-dimensional electronic mapdata, which includes modeling of a building structure, as well as to thethree-dimensional modeling method of the building structure alone.

Another application of the present invention is a three-dimensionalmodeling assist device that assists generation of three-dimensionalelectronic data of a building structure. In one preferable embodiment,the three-dimensional modeling assist device of the invention has animage data input mode, a shooting information input module, a virtualspace display module, a projection module, and a model display module.The image data input module and the shooting information input modulerespectively input a photograph and a planar shape of the buildingstructure, and a shooting parameter. The virtual space display moduledisplays an image in a direction of viewing the building structure fromthe shooting position in a virtual space set for generation of thethree-dimensional electronic data. The projection module projects thephotograph in the virtual space, based on the shooting parameter. Themodel display module displays a shape of the building structure definedby mapping of the planar shape in a direction of height. Thethree-dimensional modeling assist device thus constructed efficientlyassists the modeling of the invention.

Still another application of the invention is a three-dimensionalmodeling device that automatically generates three-dimensionalelectronic data of a building structure. In one preferable embodiment,the three-dimensional modeling device has a modeling module, in additionto the image data input module and the shooting information input moduleincluded in the three-dimensional modeling assist device discussedabove. The modeling module defines the planar shape and the shootingposition, arranges the photograph, and maps the defined planar shape ina direction of height to be matched with the photograph, so as tospecify a shape of the building structure in the direction of height.

The present invention is also directed to a data collection device thatcollects data used to generate three-dimensional electronic data of abuilding structure. In one preferable embodiment, the data collectiondevice has a shooting module, a shooting parameter acquisition module,and a data storage module. The shooting module obtains a photograph ofthe building structure in the form of electronic data. The shootingparameter acquisition module acquires a shooting parameter required tofit the photograph to an actual scene of viewing the building structurefrom a shooting position of the photograph. The data storage modulestores the obtained electronic data and the acquired shooting parametermapped to data regarding the shooting position. The data collectiondevice of such construction ensures consolidated collection of requiredinformation.

The data collection device may be constructed in the form of a tripodfor fixing a camera, but it is preferable that at least part of the datacollection device is incorporated in a digital camera. In one especiallypreferable structure, the shooting parameter acquisition module isincorporated in a camera and acquires an orientation and a focal lengthof the camera at a time of photographing.

The technique of the invention is also actualized by computer programsthat cause a computer to attain the three-dimensional modeling method,the three-dimensional electronic map data generation method, thethree-dimensional modeling assist device, and the three-dimensionalmodeling device discussed above. Another application of the invention isrecording media in which such computer programs are recorded. Typicalexamples of the recording media include flexible disks, CD-ROMs,magneto-optic discs, IC cards, ROM cartridges, punched cards, printswith barcodes or other codes printed thereon, internal storage devices(memories like RAMs and ROMs) and external storage devices of computers,and a variety of other computer readable media.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the principle of three-dimensional modeling in the presentinvention;

FIG. 2 shows the relation between a photographed image and a buildingstructure;

FIG. 3 shows the angle of view of a camera;

FIG. 4 shows the shooting direction of the camera;

FIG. 5 illustrates the construction of an electronic map data generationsystem 100 in one embodiment;

FIG. 6 illustrates the structure of an auto modeling module 120;

FIG. 7 illustrates the structure of a manual modeling module 130;

FIG. 8 illustrates the structure of a texture creation module 140;

FIG. 9 illustrates the construction of a modeling data collectiondevice;

FIG. 10 is a flowchart showing a series of three-dimensional modeling;

FIG. 11 is a flowchart showing the details of virtual spacepreprocessing;

FIG. 12 shows the significance of addition of undulations;

FIG. 13 is a flowchart showing the details of auto modeling process;

FIG. 14 shows a method of judging an overlap status;

FIG. 15 is a flowchart showing the details of manual modeling process;

FIG. 16 shows a build-up method;

FIG. 17 is a flowchart showing the details of texture creation process;

FIG. 18 shows an example of setting a point structure; and

FIG. 19 shows an example of setting a line structure.

BEST MODES OF CARRYING OUT THE INVENTION

One mode of carrying out the invention is described below in thefollowing sequence:

A. Construction of Map Data Generation System

-   -   A1. Structure of Auto Modeling Module    -   A2. Structure of Manual Modeling Module    -   A3. Structure of Texture Creation Module

B. Modeling Data Collection Device

C. Modeling

-   -   C1. Preprocessing    -   C2. Auto Modeling Process    -   C3. Manual Modeling Process    -   C4. Texture Creation Process    -   C5. Additional Structure Setting Process        A. Construction of Map Data Generation System

FIG. 5 illustrates the construction of an electronic map data generationsystem 100 (hereafter may simply be referred to as the system 100) inone embodiment. The system 100 carries out three-dimensional modeling ofa building structure to generate three-dimensional electronic map data.In this embodiment, the system 100 is actualized by the softwareconfiguration of the respective functional blocks in a computer. Thesystem is made up of one single computer in this embodiment, althoughthe system may be constructed by connection of a host computer withterminals via a network.

The functional blocks of the system 100 respectively exert the functionsdiscussed below. A data input module 101 externally inputs modelingdata. Here the modeling data represents data required forthree-dimensional modeling and includes electronic data of photographsof building structures as modeling objects, as well as their shootingpositions and shooting parameters. In this embodiment, the shootingparameters include a yaw angle, a pitch angle, and a roll angle definingthe orientation of a camera at the time of photographing (see FIG. 4)and a focal length representing an angle of view (see FIG. 3). Thesedata may be input via a medium, such as a magneto-optic disc MO, orotherwise may be input via a network or another communication.

Multiple functional blocks discussed below take charge of execution ofthree-dimensional modeling, based in the input modeling data. Apreprocessing module 110 functions to provide a virtual space used forthree-dimensional modeling in the system 100. More concretely thepreprocessing module 110 provides ground surface to build athree-dimensional model thereon. For this purpose, the preprocessingmodule 110 refers to an altitude database 103 and a two-dimensional mapdatabase 102. The altitude database 103 specifies an altitude of eachgrid square obtained by dividing the ground surface into grid squares.For example, 50 m-mesh data prepared by Geographical Survey Institute,Japan may be applicable to the altitude database 103. Thetwo-dimensional map database 102 is an existing planar map database andis used to specify a planar shape of each building structure. Data likeaerial photographs, satellite photographs, and house maps may beapplicable to the two-dimensional map database 102.

An auto modeling module 120 functions to automatically generate athree-dimensional model, based on the modeling data. A virtual spacedisplay module 104 shows the progress of modeling in the virtual spaceon a display of the system 100. The principle of auto modeling has beendiscussed previously with reference to FIGS. 1 and 2. The auto modelingmodule 120 has multiple functional blocks to carry out auto modelingbased on the principle, as discussed later.

A manual modeling module 130 functions to manually generate athree-dimensional model, in response to operations of an operator. Inthe structure of this embodiment, the object of manual modeling isbuilding structures of complicated shapes that have difficulties in automodeling. The virtual space display module 104 provides the display of avirtual space to be referred to by the operator for manual modeling. Themanual modeling module 130 has multiple functional blocks to assistmanual modeling, as discussed later.

A texture creation module 140 functions to attach a texture to eachbuilding structure generated by modeling, in response to operations ofthe operator. In the structure of this embodiment, the texture is aphotograph of the building structure. The virtual space display module104 provides the display to be referred to by the operator forattachment of the texture. The texture creation module 140 has multiplefunctional blocks to assist attachment of the texture, as discussedlater.

An additional structure setting module 150 generates, by modeling,additional structures other than the building structures to besupplemented to the electronic map data. The additional structuresinclude, for example, trees, traffic signals, and guardrails. Theadditional structures are defined by models registered in a partsdatabase 105.

An integration module 106 functions to interrelate the data generated bythe respective functional blocks discussed above and adjust the formatof the electronic map data. The integration module 106 also specifiesletters, characters, and numbers showing the building structure and theplane name, as well as various symbols and marks to be displayed on aresulting map. The integration module 106 outputs the resultingintegrated electronic map data to a map database 10. The electronic mapdata may be recorded in a DVD-ROM or another recording medium ME.

A1. Structure of Auto Modeling Module

FIG. 6 illustrates the structure of the auto modeling module 120. Theauto modeling module 120 uses the functional blocks discussed below toautomatically generate a three-dimensional model of building structures,based on the principle of FIGS. 1 and 2 as described previously.

An image edge extraction sub-module 121 extracts the edges or edge linesof each building structure specified as the modeling object from thephotograph of the building structure. The extraction of the edges is,for example, based on the tone differences among respective faces of thebuilding structure.

A base model selection sub-module 122 selects a base model used formodeling out of a base model database 123. Examples of some base modelsare given in the illustration. The base models include, for example, abuilding model MD1, a one-story house model MD2, and a two-story housemodel MD3. Each base model gives the rough contour of a buildingstructure. The procedure of the embodiment successively selects the basemodels in a preset order until an appropriate result is obtained in asubsequent matching process. The selection of the base model may bebased on information given by the two-dimensional map database.

A matching sub-module 124 carries out a matching process, which altersthe height of a selected base model to be fit to the photograph arrangedin the virtual space. The overlap status of the extracted image edgeswith each selected base model determines the result of the matching.When alteration of the height of a current option of the base modelstill fails to match the base model with the extracted image edges, thematching sub-module 124 informs the base model selection sub-module 122of the failed matching and makes a next option of the base modelsubjected to the matching process.

A wire frame creation sub-module 125 creates a wire frame of eachbuilding structure, based on the result of the matching.

A2. Structure of Manual Modeling Module

FIG. 7 illustrates the structure of the manual modeling module 130. Themanual modeling module 130 uses the functional blocks discussed below togenerate a three-dimensional model in response to the operations of theoperator.

A rising shape selection sub-module 132 selects a rising shape, inresponse to the operator's instruction. Multiple rising shapes have beendefined in advance in the form of a rising shape database 133. Examplesof some rising shapes are given in the illustration. Each rising shaperepresents a model shape defined by shifting a planar shape in thedirection of height in the virtual space. The rising shapes include, forexample, a simple vertical rise Rp1, a point-concentrated rise Rp2, aline-concentrated rise Rp3, an expansion-contraction rise Rp4, a steprise Rp5, and a dome rise Rp6. Definition of various rising shapes aimsto cover diverse shapes of building structures.

A height alteration sub-module 131 shifts a planar shape in thedirection of height according to the selected rising shape. A build-upprocess sub-module 134 builds up multiple generated models to give anintegrated model of more complicated shape. A wire frame creationsub-module 135 creates a wire frame of each building structure, based onthe processing results of the height alteration sub-module 131 and thebuild-up process sub-module 134.

A3. Structure of Texture Creation Module

FIG. 8 illustrates the structure of the texture creation module 140. Thetexture creation module 140 uses the functional blocks discussed belowto attach a texture to each building structure generated by modeling.

A repeated structure setting sub-module 141 defines a repetition area,to which an identical texture is repeatedly applied, and a residualsingle area with regard to each building structure, in response to theoperations of the operator. The repeated structure setting sub-module141 also cuts the wire frame of the building structure according to thesetting of the repetition area. A texture setting sub-module 142 sets atexture to be attached to each area. The procedure of this embodimentutilizes a cut of a photograph to set the texture. A texturemodification sub-module 143 modifies the texture as the cut of thephotograph to be fit to the surface of the model. An example of suchmodification is given in the illustration. A hatched area shows atexture as the cut of the photograph. The process of modificationincludes a change in shape of the texture, integration of or divisioninto multiple textures, and color adjustment of the texture.

A texture attachment sub-module 144 attaches the texture set accordingto the definition of the repetition area. The preset texture isrepeatedly applied to the repetition area, while being applied only onceto the single area. The texture attachment sub-module 144 stores theresults of the attachment in a texture database 145. The texturedatabase 145 maps a code defining each texture to a code defining facesto which the texture is attached.

B. Modeling Data Collection Device

FIG. 9 shows the construction of a modeling data collection device. Themodeling data collection device includes a digital still camera (DSC) 20and a data recorder 27. A typical example of the data recorder 27 is amobile computer.

The DSC 20 functions to obtain shooting parameters synchronously withphotography of a building structure. A GPS 25 is mounted on the mainbody of the DSC 20. The GPS 25 specifies the position by utilizing radiowaves from satellites, as is well known. In the structure of thisembodiment, the GPS 25 gains information on latitude, longitude, andaltitude, synchronously with a motion of a shutter 21.

An angle sensor 24 is also mounted on the main body of the DSC 20. Theangle sensor 24 gains the yaw angle, the pitch angle, and the rollangle, which define the orientation of the DSC 20 at the time ofphotographing, synchronously with the motion of the shutter 21. Theseangles are given as rotational angles about respective axes X, Y, and Zin an illustrated global coordinate system.

A lens 22 of the DSC 20 has a focal length sensor 23, which measures afocal length at the time of photographing synchronously with the motionof the shutter 21.

Data obtained by the respective sensors discussed above are transmittedto the data recorder 27 via an interface 26. The data recorder 27 storesthe transmitted data in the form of a shooting database 28. Anexemplified structure of the shooting database 28 is given in theillustration. In the illustrated example, values of a latitude ‘LAT1’, alongitude ‘LON1’, a focal length ‘FC1’, and shooting angles ‘α1, β1, γ1’are stored corresponding to a code number ‘ZN00100’ allocated to eachphotograph. Photograph data and related comments may also be stored withthese data.

In the structure of this embodiment, the respective sensors areincorporated in the DSC 20. The respective sensors may otherwise beprovided separately from the DSC 20. In one example of the latterstructure, the respective sensors may be incorporated in a tripod forfixing the DSC 20.

C. Three-Dimensional Modeling

FIG. 10 is a flowchart showing a series of three-dimensional modeling.This embodiment gives a flow of processing to model one buildingstructure. The series of processing is executed automatically or inresponse to the operator's operations in the system 100 shown in FIG. 5.

When the three-dimensional modeling process starts, the operator firstinputs modeling data into the system 100 (step S100). The modeling dataincludes the shooting parameters shown in FIG. 9 and a photograph.

The operator then carries out modeling of a building structure, based onthe input modeling data. The modeling process includes a virtual spacepreprocessing step (step S200), an auto modeling step (step S300), amanual modeling step (step S400), a texture creation step (step S500),and an additional structure setting step (step S600). The system 100registers a resulting generated model into map data (step S700) tocomplete three-dimensional modeling. The details of the processing atthe respective steps are discussed below.

C1. Preprocessing

FIG. 11 is a flowchart showing the details of the virtual spacepreprocessing. This process corresponds to the functions of thepreprocessing module 110 (see FIG. 5). When this process starts inresponse to the operator's input of a command, the system 100 inputs thetwo-dimensional shape and the position of a building structure as amodeling object and altitude data in the vicinity of the buildingstructure (step S201). The procedure of this embodiment usestwo-dimensional map data to specify the two-dimensional shape and theposition of the building structure. An aerial photograph or a record atthe shooting site may be used instead, for such specification. Theprocedure of this embodiment inputs the planar shape of the buildingstructure as a complete closed figure, based on the two-dimensional mapdata. One possible modification may input only part of the buildingstructure observable in a photograph. When a rear face of the buildingstructure is unobservable in the photograph, for example, theunobservable part may be omitted from the input and the planar shape maybe input with polygonal lines. In this case, a three-dimensional modelof the building structure is completed by individually generating amodel of a front face and a model of a rear face and integrating thesemodels with each other. The position of the building structure may bespecified in an absolute coordinate system, for example, by the latitudeand the longitude, or may be specified according to the positionalrelation to the shooting position. The procedure of this embodiment usesaltitude data provided by Geographical Survey Institute for the altitudedata in the vicinity of the building structure, although this is notrestrictive at all.

The system 100 then defines a virtual space as infinite space (stepS202). A preferable procedure gives a display of the defined infinitespace seen from a certain point of view, as illustrated. A knowntechnique is applicable to three-dimensional graphical display of thevirtual space. The position of the viewpoint for the three-dimensionalgraphical display is set arbitrarily, but setting the position of theviewpoint equal to the shooting position is desirable for the smoothprogress of the subsequent processing.

After definition of the infinite space, the system 100 locates thetwo-dimensional shape of the building structure, based on the data inputstep S201 (step S203). A thick frame in the illustration represents thetwo-dimensional shape of the building structure.

The system 100 finally adds undulations to the display of the infinitespace, based on the input altitude data (step S204). The system 100 alsomodifies the two-dimensional shape of the building structure to be fitto the ground surface with the undulations added. This completes theseries of preprocessing.

FIG. 12 shows the significance of addition of the undulations. Theillustration gives a side view of the building structure and the camera.As illustrated, the ground surface has a certain altitude in thevicinity of the building structure and another altitude in the vicinityof the shooting position. Namely the ground surface does not coincidewith the level surface. The altitude of the camera DSC at the time ofshooting and the altitude of the building structure are respectivelyexpressed as ALTc and ALTb.

As clearly understood from the principle shown in FIGS. 1 and 2, themodeling method of this embodiment does not specify the height of thebuilding structure from the ground surface but specifies the position ofa top Tb of the building structure. This position Tb is determinedrelative to the shooting position of the camera DSC. Even in the casewhere the undulations of the ground surface in the virtual space are nottaken into consideration, setting the camera DSC at the altitude ALTcaccurately specifies the position of the top Tb or the altitude of thebuilding structure. In this case, however, the building structureincluding a space between the actual ground surface and the levelsurface (that is, a hatched area in the illustration) is subjected tomodeling. The resulting model of the building structure has a heightdifferent from the actual height and thus does not accurately reflectthe actual state. In order to prevent this potential problem, theprocedure of the embodiment adds the undulations to the ground surfaceand then locates the two-dimensional shape of the building structure onthe ground surface with the undulations.

The procedure of this embodiment carries out modeling of the buildingstructure, after addition of the undulation to the ground surface. Onemodified procedure may carry out modeling of the building structure andomit the hatched area from a resulting model by taking into account thealtitude. The addition of undulation may be omitted when there is littledifference between the altitude in the vicinity of the shooting positionand the altitude in the vicinity of the building structure.

C2. Auto Modeling Process

FIG. 13 is a flowchart showing the details of the auto modeling process.This process corresponds to the functions of the auto modeling module120 (see FIGS. 5 and 6).

When the auto modeling process starts, the system 100 locates aphotograph PIC of the building structure in the virtual space. Thearrangement of the photograph is also shown in the illustration. Theorigin O represents the shooting position set in the virtual space. Theshooting parameters specify the angle of view θ and the shootingdirection at the time of photographing. The shooting direction definedby the yaw angle and the pitch angle at the time of shooting is shown bythe one-dot chain line. The photograph is located in the virtual spaceunder restriction of conditions that the photograph is to be locatedvertical to the one-dot chain line and that both ends of the photographcorrespond to a range defined by the angle of view θ (see E1 and E2 inthe illustration). For an inclination-free, upright display of thebuilding structure in the virtual space, the photograph is rotated aboutthe one-dot chain line, based on the roll angle at the time of shooting.

After the arrangement of the photograph, the system 100 extracts theedges of the image (step S304). The extraction of the image edges isalso shown in the illustration. As shown in the left-side drawing, thephotograph of the building structure has different tones on respectivefaces across the edges as the boundaries by the effects of the lightray. The system 100 extracts the edges of the building structure, basedon the tone differences. This method is, however, not restrictive, andany of other diverse methods is applicable to the extraction of theedges.

On completed extraction of the edges, the system 100 successivelyselects base models and carries out the matching process to judge theoverlap status (step S306). The base models have the various shapes asdiscussed above with reference to FIG. 6. The procedure of thisembodiment selects one option of the base model and carries out thematching process. In the case of an unsatisfactory result of thematching, the procedure determines that selection of the current optionof the base model is inadequate and selects a next option of the basemodel in a preset order.

FIG. 14 shows a method of judging the overlap status. The bottomdrawings show the procedure of matching. The left-side drawing shows anedge-extracted model from the building structure as the modeling object.The system 100 changes the height of a base model in multiple stages asPa, P2, . . . , and judges the overlap status of an extracted edge witha line segment included in the selected base model. For example, thesystem 100 judges the overlap status of the parts pointed by the arrowwith regard to a height P3.

A method shown by the upper drawings is, for example, applied to thejudgment of the overlap status. The procedure defines a region A1 of afixed width around an edge L1 shown by the solid line. In a similarmanner, the procedure defines a region A2 of a fixed width around a sideL2 of the base model shown by the dotted line. The positional relationbetween the edge L1 and the side L2 specifies an overlap (a hatched areain the illustration) of the regions A1 and A2. The area of the overlapvaries with a variation in height of the base model. For example, anincrease in height of the base model first increases and then decreasesthe area of the overlap, as shown by the left-to-right change of thedrawings. This variation is shown in a center graph. The matching ratiorepresents the area of the overlap to the total area of the regions A1and A2. As shown in this graph, the matching ratio gradually increaseswith an increase in height of the base model, reaches the maximum at aheight P6, and then decreases. The system 100 determines the state ofmatching of the extracted edge with the base model at the height P6,based on the variation in matching ratio. The procedure may furtherdivide the part around the height P6 into smaller sections and make eachsmaller section subjected to the matching process. This method is notrestrictive at all, and any of other diverse methods is applicable tothe judgment of the overlap status.

On completion of the matching, the system 100 specifies the height ofthe eventually selected base model, based on the result of the matching,and creates a wire frame of the building structure as the modelingobject (step S308).

C3. Manual Modeling Process

FIG. 15 is a flowchart showing the details of the manual modelingprocess. This process corresponds to the functions of the manualmodeling model 130 (see FIGS. 5 and 7).

When the manual modeling process starts in response to the operator'sinput of a command, the system 100 locates a photograph in the virtualspace (step S402). The arrangement of the photograph follows theprocedure at step S302 in the auto modeling process (FIG. 13). Thephotograph located in the virtual space is shown on the display of thesystem 100.

The operator selects a rising shape and carries out a matching process,based on the planar shape and the photograph arranged in the virtualspace (step S404). The operator checks the shape of the buildingstructure and selects a rising shape, which is expected to be suitablefor the shape of the building structure, among the options as shown inFIG. 7. In response to the operator's instruction of a height in thevirtual space, the system 100 generates and displays a model of theselected rising shape and the instructed height in the virtual space.The operator then performs the matching process, which adjusts theheight to make the display of the model matched with the photograph. Avariety of methods may be applicable to the instruction of the height.From the viewpoint of easiness in operation, one desirable method uses apointing device like a mouse to give an instruction on the display ofthe virtual space.

The manual modeling technique is adopted to generate a model ofcomplicated shape, which has difficulties in auto modeling. The simplematching process may not ensure a satisfactory result of modeling for abuilding structure of complicated shape. The manual modeling techniqueproceeds to a build-up process for modeling the building structure ofsuch complicated shape (step S406). The outline of the build-up processis also given in the illustration. The build-up process is adopted togenerate a model of a building structure having different planar shapesin an upper layer and in a lower layer, like an illustrated example.Integration of a lower-layer model with an upper-layer model completes afinal model of the building structure. The build-up process accordinglyinvolves integration of multiple models. Integration of multiple modelsis not restricted to a stack in the vertical direction but may be analignment in the horizontal direction.

FIG. 16 shows a method of the build-up process. The illustration gives ascreen window open on a display DISP of the system 100. The screenwindow includes a three-dimensional display VL of the virtual space onthe left and a two-dimensional display VR on the right side. Thephotograph of the building structure is omitted from the illustration.

The two-layered building structure shown in FIG. 15 has an upper-layerplanar shape OBJin and a lower-layer planar shape OBJout. The operatorshifts the lower-layer planar shape OBJout in the direction of height tocreate a lower-layer model LE1, which is given on the left side of theillustration. In the procedure of this embodiment, the upper-layerplanar shape OBJin does not affect the lower-layer model LE1 in thisstage. Namely the planar shape OBJin is simply located above thelower-layer model LE1, and the shape of the model LE1 does not dependupon the setting of the planar shape OBJin.

The operator subsequently shifts the upper-layer planar shape OBJin inthe direction of height to create an upper-layer model LE2. In theprocedure of the embodiment, the upper-layer model LE2 is formed abovethe top face of the lower-layer model LE1. This step-by-step approachimplements modeling of a multi-layered building structure. This methodof the build-up process is only illustrative and not restrictive at all.One possible modification may, for example, create the lower-layer modelLE1 having a hollow space on the center thereof, in which theupper-layer model LE2 is to be located, create the upper-layer model LE1on the ground surface, and integrate the upper-layer model LE2 with thelower-layer model LE1. Another possible modification may create thelower-layer model LE2 having the identical shape with that of theembodiment, create the upper-layer model LE1 on the ground surface, andintegrate the lower-layer model LE1 with the upper-layer model LE2 byBoolean operation.

The illustrated example of FIG. 16 has the known lower-layer andupper-layer planar shapes. When the upper-layer planar shape OBJin isunknown, the operator may be allowed to define the planar shape ineither the three-dimensional display VL or the two-dimensional displayVR. The definition may be implemented before modeling of the lower layeror after modeling of the lower layer and before modeling of the upperlayer.

On completion of the matching and the build-up process, the system 100specifies the height of the completed base model, based on the result ofthe matching and the build-up, and creates a wire frame of the buildingstructure as the modeling object (step S408).

C4. Texture Creation Process

FIG. 17 is a flowchart showing the details of the texture creationprocess. This process corresponds to the functions of the texturecreation module 140 (see FIGS. 5 and 8).

When the texture creation process starts, the operator first defines arepeated structure (step S502) to set a repetition area, to which anidentical texture is repeatedly applied, and a residual single area. Anexample of the repeated structure is given in the illustration. Thehatched portion corresponds to the repetition area. When respectivestories have a similar structure as in the case of an office building,the repetition area may be set in the unit of story. The portion otherthan the repetition area is defined as the single area.

The repetition area is defined as the unit of attachment of the textureand may thus not correspond to the actual status of the buildingstructure. For example, a building structure shown in the center drawinghas a repeated structure of multiple stories on a front face but anintegral side face. With regard to this building structure, theprocedure may set a repetition area in the unit of story on the frontface, while setting a single area on the side face.

On completion of definition of the repeated structure, the operator setsa texture (step S504). Here the texture is created, based on thephotograph of the building structure. This photograph may be the same asthat used for three-dimensional modeling. The procedure of thisembodiment, however, uses a photograph showing the front side of thebuilding structure to relive the load of adapting the texture to themodel. At the texture setting step, the operator cuts off part of thephotograph as the texture and performs required modification includingchanges in shape and tone of the cut-off texture to fit the surface ofthe model. The modification includes integration of and separation intomultiple textures.

On completion of setting the texture, the system 100 executes attachmentof the texture in response to the operator's command (step S506). Theillustration also shows attachment of the texture to the repetitionarea. The left-side drawing shows a photograph of a building structure,and the right-side drawing shows a resulting created model. Asillustrated, the model is completed by repeatedly attaching thephotograph of the top story to the respective stories. In many cases,trees and other obstacles are present on the front side of a buildingstructure, so that it is difficult to gain the texture of the wholebuilding structure. The procedure of the embodiment defines therepetition area and utilizes the texture of a best-shot part, such asthe top story of the building structure. This ensures relatively easyattachment of the texture to the whole building structure. In theillustrated example, the texture for the repetition area is also used asa single texture to be attached to a single area on the first story. Adifferent texture may alternatively be used for the single texture.

C5. Additional Structure Setting Process

The additional structure setting process corresponds to the functions ofthe additional structure setting module 150 (see FIG. 5). This processdefines additional structures in the vicinity of a building structure,separately from modeling of the building structure itself. The procedureof this embodiment arranges a preset model of additional structures inresponse to the operator's operations. The additional structures areclassified by the specification method of arrangement into pointstructures and line structures.

FIG. 18 shows an example of setting a point structure. The pointstructure represents an additional structure, of which model is locatedby specifying one point, at which the additional structure is to bearranged. Small-sized examples of the point structure include trafficsignals, street lamps, telephone poles, postboxes, bus stops, phonebooths, roadside trees, and traffic signs. Large-sized examples of thepoint structure include steel towers of high-tension cables, relaystations of cellular phones, gas stations, and various chain stores,such has CVS, having standardized shapes. Such point structures may becreated by the conventional three-dimensional modeling technique,instead of the modeling technique of this embodiment.

The illustration shows a display when a traffic signal is arranged as anexample of the point structure. As mentioned previously, thethree-dimensional display VL in the virtual space is shown on the leftside of the display DISP, and the two-dimensional display VR on theright side. The operator selects the type of the point structure andspecifies a setting point of the selected point structure in thetwo-dimensional display VR as shown by the arrow. This gives a modelAdd1 of traffic signal in the three-dimensional display VL. In the caseof a street tree or any equivalent structure, the height may also be setin the three-dimensional display VL.

FIG. 19 shows an example of setting a line structure. The line structurerepresents an additional structure, of which model is located byspecifying a linear range, on which the additional structure is to bearranged. Examples of the line structure include guardrails, walls,fences, white lines drawn on roads, such as zebra crossings, bridges andequivalents of various shapes, and central reserves. Such linestructures may also be created by the conventional three-dimensionalmodeling technique. A base model having a unit length is registered inadvance for each line structure. The base model is repeatedly appliedover a specified range.

The illustration shows a display when a guardrail is arranged as anexample of the line structure. Specification of a linear range, that is,specification of a start point and an end point of a line segment, inthe two-dimensional display VR as shown by the arrows gives a model Add2of guardrail in the three-dimensional display VL.

D. Effects

The electronic map data generation system of the embodiment discussedabove completes three-dimensional modeling without actually measuringthe height of the building structure. Namely the technique of theinvention ensures accurate modeling of the building structure withrelatively light load.

The series of processing shown in FIG. 10 and subsequent drawingsdescribes the procedure of modeling a single building structure. Whenone photograph includes multiple building structures, the technique ofthe invention is applicable to parallel modeling of the multiplebuilding structures. This ensures efficient generation of thethree-dimensional electronic map data.

The procedure of the embodiment uses the texture based on the photographof the building structure and thereby enhances the touch of reality inmodeling. Application of the repeated structure effectively relives theoperator's load in attachment of the texture.

E. Modification

The embodiment regards the procedure of modeling with the photographtaken on the ground. The photograph used for this purpose is notrestricted to those taken on the ground, as long as the shootingparameters and the shooting position are known. For example, an aerialphotograph of cross shot of the building structure may be used instead.The aerial photograph having the known shooting parameters and shootingposition is preferably used for efficient three-dimensional modeling ina wider range.

The procedure of this embodiment follows the steps shown in FIG. 10 toeffectuate modeling. Either auto modeling or manual modeling may beomitted, if not necessary. The texture creation process and theadditional structure setting process are carried out to add the touch ofreality, and may be omitted according to the applications of modeling.

The embodiment discussed above is to be considered in all aspects asillustrative and not restrictive. There may be many modifications,changes, and alterations without departing from the scope or spirit ofthe main characteristics of the present invention. For example, theseries of control processing may be actualized by the hardwareconstruction, instead of the software configuration.

INDUSTRIAL APPLICABILITY

The present invention is directed to the three-dimensional modelingmethod of generating three-dimensional electronic data of a buildingstructure. The technique of the invention is applicable to the field ofgenerating three-dimensional electronic map data by taking advantage ofthe three-dimensional modeling method.

1. A three-dimensional modeling method of generating three-dimensionalelectronic data of a building structure, said three-dimensional modelingmethod comprising the steps of: (a) inputting a photograph and ahorizontal planar shape of the building structure expressed byelectronic data; (b) inputting a positional relation between a shootingposition of the photograph and the building structure and a shootingparameter that specifies a viewing direction and an angle of view at atime of photographing; (c) defining the planar shape of the buildingstructure and the shooting position in a virtual space set forgeneration of the three-dimensional electronic data, based on the inputpositional relation, and arranging the photograph at a position definedby the input shooting parameter in the virtual space; and (d) specifyinga height of the building structure by raising the defined planar shapeof the building structure in the virtual space to reach an extension ofa virtual line that connects the shooting position defined in thevirtual space with a top of the building structure in the photographarranged in the virtual space, so as to specify a shape of the buildingstructure in the direction of height.
 2. A three-dimensional modelingmethod in accordance with claim 1, wherein the planar shape is specifiedby a two-dimensional plane map including the building structure.
 3. Athree-dimensional modeling method in accordance with claim 1, whereinsaid step (c) defines a three-dimensional base model giving a roughcontour of the building structure, as well as the planar shape.
 4. Athree-dimensional modeling method in accordance with claim 1, whereinsaid step (d) comprises the sub-steps of: analyzing the photograph tospecify an edge of the building structure; quantitatively analyzing anoverlap status of a side of the planar shape with the specified edge inthe course of the raising; and selecting a raising position at which theoverlap status becomes a local maximum, so as to specify the height ofthe building structure.
 5. A three-dimensional modeling method inaccordance with claim 1, said three-dimensional modeling method furthercomprising the step of: inputting altitude data representing an altitudeof ground surface in the vicinity of the building structure, prior tosaid step (c), wherein said step (c) comprises the sub-step of makingthe input altitude data reflect on the ground surface in the vicinity ofthe building structure, and said step (d) specifies the shape of thebuilding structure in the direction of height, above the ground surface.6. A three-dimensional modeling method in accordance with claim 1, saidthree-dimensional modeling method further comprising the step of: (e)attaching at least part of the photograph as a texture to surface of aresulting model of the building structure having the shape in thedirection of height specified in said step (d).
 7. A three-dimensionalmodeling method in accordance with claim 6, wherein said step (e)comprises the sub-steps of: defining a repetition area, to which asimilar unit structure is repeatedly applied, and a residual single areaother than the repetition area on the surface of the building structure;and repeatedly attaching a texture of the unit structure to therepetition area, whether an actual structure is included or not includedin the photograph.
 8. A three-dimensional modeling method in accordancewith claim 1, wherein the electronic data expressing the photograph ofthe building structure do not include height data of the buildingstructure.
 9. A three-dimensional modeling method in accordance withclaim 1, wherein the height of the building structure is not separatelydetermined or obtained prior to raising the defined planar shape of thebuilding structure in the virtual space.
 10. A three-dimensionalmodeling device that generates three-dimensional electronic data of abuilding structure, said three-dimensional modeling device comprising: afirst input module that inputs a photograph and a horizontal planarshape of the building structure expressed by electronic data; a secondinput module that inputs a positional relation between a shootingposition of the photograph and the building structure and a shootingparameter that specifies a viewing direction and an angle of view at atime of photographing; and a modeling module that defines the planarshape and the shooting position in a virtual space set for generation ofthe three-dimensional electronic data, based on the input positionalrelation, arranges the photograph at a position defined by the inputshooting parameter in the virtual space, and specifies a height of thebuilding structure by raising the defined planar shape in the virtualspace to reach an extension of a virtual line that connects the shootingposition defined in the virtual space with a top of the buildingstructure in the photograph arranged in the virtual space, so as tospecify a shape of the building structure in the direction of height.11. A three-dimensional modeling device in accordance with claim 10,wherein said modeling module comprises: an edge analysis sub-module thatanalyzes the photograph to specify an edge of the building structure;and an overlap status analysis sub-module that quantitatively analyzesan overlap status of a side of the planar shape with the specified edgein the course of the raising, and selects a raising position at whichthe overlap status becomes a local maximum, so as to specify the heightof the building structure.
 12. A data collection device that collectsdata used by a three-dimensional modeling device in accordance witheither one of claims 10 and 11 to generate three-dimensional electronicdata of a building structure, said data collection device comprising: ashooting module that obtains the photograph of the building structure inthe form of electronic data; a shooting parameter acquisition modulethat acquires the shooting parameter; and a data storage module thatstores the obtained electronic data and the acquired shooting parametermapped to data regarding the shooting position.
 13. A data collectiondevice in accordance with claim 12, wherein said shooting module is adigital camera, and said shooting parameter acquisition module isincorporated in said digital camera and acquires an orientation and afocal length of said camera at a time of photographing.
 14. Athree-dimensional modeling device in accordance with claim 10, whereinthe modeling module does not separately determine or obtain the heightof the building structure prior to raising the define planar shape inthe virtual space.
 15. A recording medium in which a computer program isrecorded in a computer readable manner, said computer program causing acomputer to assist generation of three-dimensional electronic data of abuilding structure, said computer program causing the computer to attainthe functions of: inputting a photograph and a horizontal planar shapeof the building structure expressed by electronic data; inputting apositional relation between a shooting position of the photograph andthe building structure and a shooting parameter that specifies a viewingdirection and an angle of view at a time of photographing; defining theplanar shape and the shooting position in a virtual space set forgeneration of the three-dimensional electronic data, based on the inputpositional relation, and arranging the photograph at a position definedby the input shooting parameter in the virtual space; and specifying aheight of the building structure by raising the defined planar shape ofthe building structure in the virtual space to reach an extension of avirtual line that connects the shooting position defined in the virtualspace with a top of the building structure in the photograph arranged inthe virtual space, so as to specify a shape of the building structure inthe direction of height.
 16. A computer program in accordance with claim15, wherein the height of the building structure is not separatelydetermined or obtained prior to raising the defined planar shape of thebuilding structure in the virtual space.
 17. A method of constructing athree-dimensional model of a building structure in a virtual space,wherein the three-dimensional model of the building structure has awidth, a depth, and a height in the virtual space, the methodcomprising: defining a viewing position in the virtual space from wherethe three-dimensional model of the building structure is to be viewedduring its construction; arranging a photograph of the buildingstructure in the virtual space in relationship to the viewing position,such that viewing the building structure in the photograph from theviewing position in the virtual space is spacially equivalent to viewingthe building structure through a camera used to shoot the photographfrom a shooting position in a real space at a time when the photographis taken; arranging a two-dimensional model that represents a base ofthe building structure in directions of the width and the depth in thevirtual space in relationship to the viewing position, such that thetwo-dimensional model coincides with a corresponding base of thebuilding structure in the photograph when viewed from the viewingposition; and without separately determining or obtaining the height ofthe three-dimensional model of the building structure in the virtualspace, extending the two-dimensional model in a direction of height toobtain the three-dimensional model of the building structure in thevirtual space, such that a top of the three-dimension model of thebuilding structure coincides with a corresponding top of the buildingstructure in the photograph when viewed from the viewing position. 18.The method in accordance with claim 17, wherein the photograph of thebuilding structure is arranged in the virtual space in relationship tothe viewing position based on a viewing direction and a viewing angle ofviewing the building structure through the camera used to shoot thephotograph from the shooting position in the real space at the time whenthe photograph is taken.